Wireless receiver



Nov. 5, 1935.

R. K. SPENCER 2,020,126

wIRELEs RECEIVER Filed Aug; 1, 1930 '-J|mu v mm:

' Inventor-z Richard Kimberley Spencer;

' Attorn Patented Nov. 5, 1935 I UNITED STATES PATENT OFFICE WIRELESS RECEIVER ration of Delaware Application August 1, 1930, Serial No. 472,292 In Great Britain September 5, 1929 3 Claims. (01. 179-171) The present invention relates to wireless receivers of the type adapted for the reception upon either of two bands of wavelength at will.

According to the present invention a wireless receiver of the type referred to is provided with two circuits, one of these circuits having a fixed resonant frequency within one of the wave bands to be received and the other having a fixed resonant frequency-within the other band, both of these circuits being operative when receiving upon either band. The invention may be applied when more than two wave bands are to be dealt wit The invention is illustrated by way of example in the accompanying drawing.

Referring to the drawing, the high frequency portion of a wireless receiver comprises two high frequency amplifying valves V1 and V2 followed by a detector valve V3. The anodes of the high frequency amplifiers V1 and V2 are connected to a source of high tension current a through high frequency choke coils b and 0 respectively, and the anode of the first valve V1 is connected to the grid of the second valve V2 through a condenser d. The anode of the second valve V2 is similarly connected to the grid of the detector valve V3 through a condenser e. The grid circuit of the first valve V1 is connected. by means of a suitable switch f to either of two inductances y and h tunable by means of a variable condenser 2' connected in parallel therewith and this circuit is coupled to the aerial and earth circuit 1'. One of the tunable inductances g and h is used for reception on one wave-band and the other for the other wave-band.

The two chokes b and c in the anode circuits are so designed in relation to their associated capacities (which may be the self capacity of the coils) that one of them has a resonant frequency within one band of wave lengths to be received and the resonant frequency of the other choke lies within the other band of Wave lengths. The coil capacities are indicated by the dotted condensers k and l.

The invention enables the maximum average amplification over the two wave bands to be obtained without loss of stability.

If desired, condensers may be added to the inherent capacities tuning the chokes but the use of such condensers is preferably avoided.

I claim:

1. An electric valve amplifier including in combination, a plurality of electric valves arranged 5 in cascade relation to each other and provided with interstage coupling means each including a single choke coil device, each of said choke coils being resonant within separate frequency bands broadly at fixed frequencies, and means for tun- 10 ing the input circuit of the amplifier selectively within each of said separate signal bands.

2. An electric valve amplifier including in combination, a plurality of electric valves arranged in cascade relation to each other and provided 16 s with interstage coupling circuits tuned to respond to signals on separate frequency bands, an input circuit for the amplifier, means for tuning said input circuit selectively to each of said separate signal bands, said tuning means including a va- 20 riable condenser, a plurality of inductances, and a switching device for selectively connecting said inductances separately each with said variable condenser, and said coupling circuits between said valves each including a single impedance 25 coupling element, one of which is in the form of a choke coil resonant at a fixed predetermined signal frequency within one of said bands, and another of which is in the form of a choke coil resonant at another fixed predetermined signal frequency within another of said bands.

3. A multi-range radio receiving system including in combination a plurality of thermionic valves connected in cascade, an input circuit for said system constituted by a plurality of inductors and a condenser, a switching device for selectively connecting one or another of said inductors with said variable condenser to determine to which of several signal bands the system will respond, and a single coupling means of the fixed'tuned type between two successive amplifying valves resonant at a radio frequency within one of said bands and a second single coupling means of the fixed tuned type between two other successive amplifying valves resonant tov a radio frequency within the other of said bands.

RICHARD KIM'BERLEY SPENCER. 

